In many fields (e.g., medicine, manufacturing, veterinary science, scientific research, etc.), it is often necessary to examine a subject and communicate the results of the examination to a remote place. Such information exchanges are especially desirable in the medical arena where it is often useful for medical practitioners to communicate medical information, such as patient test results, e.g., radiology studies or cardiac studies, to other practitioners located in remote places. Telemedicine facilitates this exchange of information. Telemedicine is generally the electronic transmission of medical data from one location to another for purposes of interpretation and consultation. Telemedicine is gaining interest in the medical community, in part due to an increasing shift in health care delivery from hospitals to physician offices, extended care facilities, ambulatory treatment centers and patients' homes.
The medical information communicated by telemedicine systems may be derived from a variety of different medical modalities. Such modalities may include sophisticated radiology equipment grouped as small matrix size and large matrix size instruments. Small matrix size systems include equipment for magnetic resonance imaging (MRI), computed tomography (CT), ultrasonography (US), nuclear medicine (NM) and digital fluorography. Large matrix size systems include equipment for computer radiography (CR) and digitized radiography (DR). Other data image acquisition equipment may be used for radiofluoroscopy, angiography, such as x-ray angiography and heart scanning. Still other equipment of great usefulness in acquiring medical information includes secondary capture devices for video, endoscopy, microscopy, and photography, such as digital cameras, scanners, electrocardiogram (ECG) machines, and the like.
The resulting medical information may take numerous forms, including text, images and video, or variations thereof, such as image overlay data, measurements, coordinates, etc. Information may also be in the form of time-dependent data including sound, such as audio dictation, and waveform data. The data may be static representations of time-dependent forms, such as curves. Thus, it is advantageous for telemedicine systems that may need to transfer the data and/or information to be flexible, so as to accommodate this variety of information/data from multiple modalities.
Typically a medical study on a patient results in a very large data file which may include a combination of data forms. For example, an MRI study on a patient may include text and about 100 images, each of which may be 300 to 500 Kb in size, loading to a study of 50 to 80 Mb total of data. This large amount of data presents a particular problem for the rapid sharing of medical information. Time is often of the essence during healthcare decision making. For example, an attending practitioner may need to obtain immediate advice on caring for a patient from a remotely located specialist. Therefore, it is critical that telemedicine systems transfer large data files in a timely fashion.
It is also important that telemedicine systems provide for the transfer of such large amounts of data without data loss. Some medical industry standards require that medical information transferred by telemedicine systems maintain sufficient detail for accurate interpretation by the practitioner. Multi-specialty DICOM Standards describe acceptable parameters to manage delivery of multimedia medical information. The DICOM Standards were originally published by an ACR-NEMA committee sponsored by the American College of Radiology and the National Electrical Manufacturers Association as Digital Imaging and Communications in Medicine (DICOM), NEMA Publications PS 3.1-PS3.12, by The National Electrical Manufacturers Association, Rosslyn, Va., 1992, 1993, 1994, 1995. These DICOM Standards define the form and flow of electronic messages that convey images and related information between computers through TCP/IP. Therefore, it is desirable for medical information transfer systems to acquire and transmit complex data, such as radiology images, in a manner that complies with the DICOM Standards. See, e.g., Bidgood, et al., “Understanding and Using DICOM, the Data Interchange Standard for Biomedical Imaging,” J. Am. Med. Informatics Assoc., 4:3, 199-212, May-June, 1997. The transferred information should be presented in the context and form that is most helpful for practitioners to make sound health and wellness decisions.
The medical profession is also under a strict duty to protect the confidentiality of patients' medical records. Thus, protection of medical data/information in telemedicine is of paramount importance. Most telemedicine systems include some form of security measures such as the use of passwords. Password identification determines whether a user is authorized to gain access to a system. However, passwords are insufficient mechanisms to maintain patient confidentiality from intruders who gain knowledge of a user's password to log onto a system and “man in the middle” attacks on the Internet.
For secure and fully private long distance communications, point-to-point connections between sites have been employed. Private networks, such as wide area networks (WAN's), are typical. Unfortunately, these systems are inflexible and involve prohibitive costs. Large telemedicine networks that span long distances, e.g. across continents, become too costly for current conventional private WAN architecture. Since all sites must be hardwired, the addition of new sites to the network is inconvenient. A medical enterprise must install and support terminal equipment and software for each WAN site. Furthermore, the volume of information designated to travel over the network may overload the system. For example, rural medical sites may only have access to poorly maintained telephone lines that are an inadequate medium for transmission of medical data.
Public networks provide a flexible and inexpensive option for long distance internetworking. Each of the remote sites in a medical network need only be connected to a local Internet provider. Adding new connections is simple and inexpensive. Once connected to a local Internet provider, a site can quickly connect to any destination around the world allowing a practitioner at one location to interpret medical test results and consult with another practitioner located elsewhere.
There are few places of the globe that the Internet can not reach. Medical information transfer systems that employ the Internet may allow for remote locations, such as third world countries that do not have an attending specialist, to access needed medical expertise. Furthermore, emergency care may be provided where a practitioner is temporarily away, e.g., at home or on vacation. See, e.g., Thrall J H, Boland G., “Telemedicine in practice”, Seminars in Nuclear Medicine 28(2):145-57, April 1998.
However, traditionally medical networks have avoided transfer of information over the Internet, in part, because of security constraints. The Internet includes public segments, where the same infrastructure is shared by potential competitors, hackers, and the like. Such public networks expose the medical enterprise to at least the following two dangers: (1) unauthorized Internet access into the medical network and (2) eavesdropping on and tampering with a communication as it passes through the Internet.
A virtual private network (VPN) may use both private and public network segments or entirely use public segments e.g., the Internet, to link resources together into a single network. Encryption technology employed at connections between private and public networks can be used to protect the data transferred between such networks as if the connection between them was entirely private. Such use of encryption in virtual private networks provides some security measures for the transfer of sensitive information.
Another problem with the use of the Internet is that the heavy traffic flowing over public connections may lead to delay problems in the transfer of the large amounts of data. Most Internet systems are not structured to allow for quick transfer of the volume of data files that are typical of medical information. Transfer efficiency depends on, inter alia, characteristics of the network segments that the packets must traverse, congestion on those segments and efficiency of the dispatcher. High delay environments include satellite connections, national links and international links.
Furthermore, where more data is attempting to flow between two points than a public system can handle, the data packets are simply thrown away by overloaded routers. Lost packets must be resent by the dispatcher, typically in a manner that is time consuming and renders the telemedicine system unusable. Transfer systems used to transmit data compliant with DICOM standards are usually designed to abort incomplete file transmissions and to restart the transfer from the beginning of the file, rather than just resending the failed packets. Telemedicine systems that employ mechanisms used to compensate for latency and loss of data in transfer are of great interest.
Moreover, typical transfer systems that are used to transmit DICOM compliant data are not appropriately configured to transfer data over the Internet. These systems have IP addresses that are suitable to destinations within a local area network. However, often these same IP addresses are unacceptable for the routers on the Internet. This factor, compounded with an overall shortage of routable IP addresses available for transfer systems in general, makes transfer of medical data directly from medical modalities across the Internet complicated.
Thus, in light of the shortcomings of the various currently available systems, there is still a need for secure medical transfer systems that allow for transfers of large amounts of data in a timely and efficient manner. In particular, there is a desire for telemedicine systems that use an encrypted and reliable Internet protocol to create a protected communication pipeline. Moreover, there is a need for systems that can move DICOM or other medical data between hosts by providing routable IP addresses.